This project will address the determination of the secondary and tertiary structures of the prion protein, PrP. The still unknown function of PrP may be partly revealed by structure determination of the protein or its domains. This structural information is also important for understanding the relationship of PrP to other proteins of known structure and function. Structural information is required to map amino acid mutations to the physical positions in the protein. This mapping in conjunction with the mutational analysis of biological function in Project 2 should link the structure and function of PrP. A combination of physical methods including spectroscopy and X-ray diffraction will be used for these studies. The mole fraction of secondary structure of PrP, a helices, b sheet and coil, will be determined for PrP, or fragments thereof, using ATR-FTIR and CD spectroscopy on natural and synthetic material. In a separate study, the central core of the PrP molecule, PrP 92-228 will be expressed in milligram amounts, purified and crystallized for X-ray crystallography. A bacterial expression system is partly developed to accomplish this end.